Related Experiment Video
Updated: Sep 26, 2026

Loading a Calcium Dye into Frog Nerve Endings Through the Nerve Stump: Calcium Transient Registration in the Frog Neuromuscular Junction
Published on: July 8, 2017
Diphenylhydantoin reduces veratridine-induced sodium permeability in frog skeletal muscle
Abstract:
The effect of the anti-epileptic drug 5,5'-diphenylhydantoin (Dilantin) on Na permeability (PNa) in frog skeletal muscle was studied. Because there is no detectable tetrodotoxin-sensitive Na permeability in resting frog muscle, PNa was induced using the alkaloid 'neurotoxin' veratridine. Veratridine has been previously characterized as a useful 'tool' for producing a population of open Na channels in frog muscle. The amount of sodium permeability produced by veratridine was quantified in two ways: by measuring (a) membrane potential (Vm) and (b) 22Na influx. Dilantin was shown to reverse veratridine-induced depolarization by approximately one-third and to inhibit veratridine-induced Na influx in a dose-dependent manner, with an apparent Km of 78 +/- 8 microM.
Related Concept Videos
Depolarizing Blockers: Mechanism of Action
Succinylcholine is the most commonly used depolarizing blocker. Chemically, it constitutes two molecules of acetylcholine joined together by an acetate methyl group. They act on the receptors in the same way as acetylcholine. Because succinylcholine...
Antihypertensive Drugs: Potassium-Sparing Diuretics
Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers
Class 1A Antiarrhythmic Drugs: These drugs work by moderately blocking sodium channels,...

